Thermofixing apparatus for synthetic-resin slide-fastener

ABSTRACT

An apparatus for thermofixing continuous synthetic-resin slidefastener coupling elements of the coil or meander type has an elongated shaping member formed with a series of beds that snugly receive the coupling-element turns to set or form the shape thereof. A source of electric energy is coupled to a portion of this member to heat it and thereby conductively heat the element along the heated portion. The member can be an endless band which is intermittently or continuously displaced over contacts which pass a current through it to heat it, or through a coil to heat it inductively. Downstream of the heating station the band is cooled, prior to detachment therefrom of the thermofixed coupling element. The contacts can comprise a pair of spaced-apart rollers connected to one side of the electric-power source and therebetween another contact connected to the other side of the source.

United States Patent 1191 Heimberger Y 111 3,770,361 1 Nov. 6, 1973 v[75] Inventor:

v [22] Filed:

1 THERMOFIXING APPARATUS FOR SYNTHETIC-RESIN SLHDE-FASTENER Helmut Heimberger, Grenzach, Germany [73] Assignee: Opti-l-loldingAQGlarus,

Switzerland Feb. 16, 1971 [21] Appl. No.: 115,395

[30] Foreign Application Priority Data 425/174 S,'391, 404, 445, 446, 455, 814; 24/213 C, 224 W; 264/230, 280, 281, 285

[ 56] References Cited UNITED STATES PATENTS 3/1946 Te Grotenhuis 425/174 HE 10/1965 Lemettrc 425/174 HD Primary Examiner-H. A. Kilby, Jr. Att0meyl(arl F. Ross [57] ABSTRACT "An apparatus for thermofixing continuous syntheticresin slide-fastener coupling elements of the coil or meander type has an elongated shaping member formed with a series of beds that snugly receive the couplingelement turns to set or form the shape thereof. A source of electric energy is coupled to a portion of this member to heat it and thereby conductively heat the element along the heated portion. The member can be an endless band which is intermittently or continuously displaced over contacts which pass a current through it to, heat it, or through a coil to heat it inductively. Downstream of the heating station the band is cooled, prior to detachment therefrom of the thermofixed coupling element The contacts can comprise a pair of spaced-apart rollers connected to one side of the electric-power source and therebetween another contact connected to the other side of the source.

9 Claims, 8 Drawing Figures PAIENIEDnuv 6 I975 SHEET 2 0F 3 INVENTOR; H. HEIMBERGER BY I 0 un ATTORNEY PAIENIEmmv 6 '97s SHEET 3 [1F 3 FIG.6

INVENTOR;

H. HEIMBERGER ATTORNEY FIG.8

THERMOFIXING APPARATUS FOR SYNTHETIC-RESIN SLIDE-FASTENER l. FIELD OF THE INVENTION The present invention relates to an appratus for thermally treating continuous multiturn syntheticresin slide-fastener elements. More particularly this invention concerns such an apparatus for the thermofixing of such shaped elements, i.e., heating and subsequent cooling to set the shape.

2. BACKGROUND OF THE INVENTION Synthetic-resin slide-fastener coupling elements are usually formed by either winding a uniaxially molecu- Iarly oriented continuous synthetic-resin 'monofilament (of a nylon-type polyamide or a polyester) about a mandrel or with a complex die-and-mandrel arrangement. The shaped'eleme'nt thus formed does not tend to keep its shape unless it is thermo-fixed. To this end it is fed. onto a wheel which has a plurality of shaping beds formed around its rim. The turns of the element aresnugly received in the beds and heated to a temperature at or just below itssoftening point to relax inter- ,nal stresses and defeat its former plastic memory expensive since they must be painstakingly milled, hardened, and ground to have an exact shape. They must also be as large as possible to prevent the finished element from having an inherent'bow and to provide a sufficiently long heating and cooling period. In addition, heating along one angular stretch of the periphery of such a wheel and cooling along another stretch creates internal stresses in the wheel that quickly damage it. In fact, the drop in the quality of the coupling elements caused by eliminating the cooling step has been found to be more acceptable than the frequent replacement of the shaping wheel.

It is also known to shape the original synthetic-resin filament-right on the teeth of the wheel, and heat the wheel itself internally; however virtually "all of the above-given disadvantages are also encountered with this method.

Another difficulty inherent in any system using such a wheel is that the travel rate of the element, in, say, meters per second, is severely limited. At the same time in installations having an intermittent advance it is difficult to design a heating arrangement that effectively and regularly heats every portion of each turn of the element.

3. OBJECTS oF THE INVENTION Another object is the provision of an apparatus for thermofixing such shaped elements which overcomes the above-given disadvantages and which can even be used for the original formation of the turns in the monofilament.

4. SUMMARY OF THE INVENTION These objects are obtained according to the present invention by an apparatus having a shaping member provided with a series of beds shaped to snugly receive the turns of a slide-fastener element and means for coupling a source of electric power to the member for heating it only along a predetermined stretch of the se-- ries of beds and thereby conductively heating the element bedded in the stretch.

According to another feature of this invention the shaping member is an endless band formed to hold two interleaved or noninterleaved coupling elements of the helicoidal or meander type. This band is heated along a predetermined portion of its length either by means of contacts arranged to pass an electric durrent through it and heat it resistively'or by means of a coil surroun ding the band along the heating stretch and energized with alternating-current to generate heating eddy currents inthe advantageously metallic conductive band.

' When high-frequency a.c. is used as the heating energy,

disadvantages. First of all, theshaping wheels are very I the high-frequency vibrations set up in the band also serve to thermofix the coupling element in accordance with principles of ultrasonic heating of plastic articles. 7

Also, the use of a.c. provides for some heating by rea-' son of the dielectric-heating principles well known in the heating of synthetic resins.

Another feature of the present invention is that downstream in the direction of advance this band is cooled by blowers or other means prior to disengagement of the treated coupling elements from this band.

In accordance with yet another feature of this invention electric'energy is conducted by three contacts which are spaced apart in the advance direction and define a heating station. The central contact is connected to one side of the electric source and the two contacts flanking it are connected to the other side. In this manner current passage around the band outside of the heating station is made impossible.

Such an apparatus offers a host of advantages over the prior-art arrangements. Mainly, the shaping band can be inexpensively produced from, say, a stock steel strip which is formed with shaping beds by means of stamping, bending or pressing and then made endless by butt-welding or soldering its ends together. Due to the close correspondence between the mass per unit length of the band and of the element only a small amount of electrical energy is needed to sufficiently heat this element, and subsequent cooling is no problem as with the relatively massive prior-art wheels, since heat is conducted from the band to the element and not vice versa. When more than two rollers are used to span and drive the endless band a very long band can be used for gradual heating and complete cooling. At the same time changing of bands is a simple and easy process that can be quickly carried out, and provision of a plurality of bands for differently dimensioned coupling elements represents no financial hardship for the manufacturer.

5. DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become apparent from the following description, reference being made to the drawing, in which:

FIG. 1 is a perspective view of a portion of a shaping according to the present invention;

FIG. 2 is a top view of the member portion shown in FIG. 1, with a pair of interleaved coupling elements engaged thereon;

FIG. 3 is a view corresponding to FIG. 1 showing an alternative embodiment of the shaping member;

FIG. 4 is a cross section through the member shown in FIG. 3 with a pair of interleaved coupling elements engaged thereon;

FIG. 5 is a view corresponding to FIG. 4, but showing a pair of noninterleaved slide-fastener stringer halves engaged on'the FIG. 3 member; and 5 FIGS. 6 8 are side views showing three embodiments of the apparatus according to the present invention.

6. SPECIFIC DESCRIPTION There is shown in'FIGS. 1 and 2 a portion of a steel band 2 having a thickness between 0.2 and 0.4 mm. This band 2 is stamped to form a plurality of beds 3 defined by a plurality of upstanding tabs or teeth 5 which are stamped out of the band leaving windows 16. Two laterally spaced rows of tabs 5 are thus formed staggered across from one another. FIG. 2 shows how the individual turns 1a of a pair of interleaved coupling coils 1 just fit between the tabs 5, in the beds 3, with these tabs 5 spacing them exactly at the desired distance. Each coil turn 1a consists of a pair of substantially parallel legs 1b lying in and defining common plane P with a bight portion 10 serving as the slidefastener coupling head. This plane P is substantially orthogonal to the axis A of each coupling coil 1. The upper leg 1b is joined to the neighboring lower leg lb via a bight portion 1d which passes around the tab 5, so that this element 1 is of the helicoidal type.

In FIG. 3 there is shown another band 2' having upstanding tabs 5' defining beds 3'. This band 2 is essentially identical to the band 2 of FIGS. 1 and 2 except that it is, as shown in FIG. 4, generally U-shaped in cross section, having no flat edg'e regions outside of the rows of tabs 5 FIG. 4 shows how a pair of turns la are interleaved on this strip 2. FIG. 5 shows how a pair of coupling elements 1 each held by stitching 17 to the.

edge of a textile support tape 6 can be engaged on the band 2', without interleaving of their heads 10. It will be understood that the coils or meanders may be preformed on a mandrel or bed and then simply placed upon the band or, alternatively, can be formed originally on the band. In either case the molecularly (unaxially) oriented thermoplastic coupling element can have a thickness of the order of that of the band.

The endless band 2 is shown in FIG. 6 spanned over a pair of rollers 7 and 8, the former being driven by a motor 18 and the latter idling. A pair of electrical wires 4 each connected to one side of an alternating-current source 9 serve to heat a region 19 of this band 2. One of the conductors 4 is in electrical contact with the two conductive rollers 7 and 8 by means of a pair of springbiased brushes 20 and the other conductor 4 is in electrical contact with the band 2 directly between these two rollers 7 and 8 by means of a brush 10. This causes the steel band 2 to be heated resistively only in the region 19 which, therefore, constitutes the heating station.

A pair of coupling elements 1 are laid into the beds 3 between the tabs 5 just upstream, relative to the direction of band displacement shown by arrow D, of the station 19. As they pass through this region they are heated sufficiently to slightly soften the synthetic-resin monofilament and relieve any internal stresses therein. On the side of the two roller 7 and 8 opposite the station 19 there are arranged a pair of blowers 12 which cool the coils l and band 2 prior to their mutual disengagement at 14. In this manner, by the time the interleaved coils l are pulled off the band 2 at 14 they are completely thermofixed.

FIG. 7 shows an arrangement having, once again, two rollers 7 and 8, plus a third roller 11. The two rollers 7 and 8 are connected to one side of the source 9 and the roller 1 1 is connected via the brush 10 to the otherside of this source. The voltage output of this source 9 is low so that a gradual but very regular heating of the band 2 between the rollers 7 and 11, and the rollers 11 and 8 is effected. Between the rollers 7 and 8 a ventilator-12 is again arranged, with the feed-on point 13 and pull-off point 14 still being located on the roller 7, as shown.

In FIG. 8 a 20 to 40 kc. source 9' is shown connected across an induction coil 15 which surrounds the band 2 .throughout the station 19. The band 2 is spanned over two rollers 21 and 22, the former being urged outwardly by a spring 23 to keep the band 2 taut. In this embodiment the band 2 is heated inductively in the station 19, thereby conductively and ultrasonically and/or dielectrically heating the coil or coils 1 bedded thereon. In all other respects this embodiment is similar to that of FIG. 6.

I claim:

1 An apparatus for thermally treating a multitum continuous synthetic-resin slide-fastener coupling element comprising:

an endless sheet-metal band provided with two transversely spaced mutually parallel upstanding rows of longitudinally spaced tongues bent from the band and forming a series of beds each snugly receiving a respective turn of the element; a source of electric power; and

' means coupling said source to said band for heating same only along a predetermined stretch of said series of beds and thereby conductively heating the element in said stretch.

2. The apparatus defined in claim 1, further comprising means for advancing said band, said means coupling said source to said band being provided along said band at a heating station.

3.'The apparatus defined in claim 2 wherein said means coupling said source to said band includes a pair of contacts engaging said band and on spaced downstream of the other, and conductors between each of said contacts and a respective side of said source.

4. The apparatus defined in claim 3 wherein said means includes a third contact engaging said band upstream of said first-mentioned contacts and a conductor connecting said third contact to the same side of the source as the furthest downstream contact.

5. The apparatus defined in claim 3 wherein at least one of said contacts is a roller.

6. The apparatus defined in claim 2, further comprising means downstream of said heating station for cooling said band.

ment and having an endless sheet-metal band provided with two transversely spaced mutually parallel upstanding rows of longitudinally spaced tongues bent from said band and forming a series of beds each receiving a respective turn of the element and means for heating the band along a predetermined stretch thereof.

i II l 

1. An apparatus for thermally treating a multiturn continuous synthetic-resin slide-fastener coupling element comprising: an endless sheet-metal band provided with two transversely spaced mutually parallel upstanding rows of longitudinally spaced tongues bent from the band and forming a series of beds each snugly receiving a respective turn of the element; a source of electric power; and means coupling said source to said band for heating same only along a predetermined stretch of said series of beds and thereby conductively heating the element in said stretch.
 2. The apparatus defined in claim 1, further comprising means for advancing said band, said means coupling said source to said band being provided along said band at a heating station.
 3. The apparatus defined in claim 2 wherein said means coupling said source to said band includes a pair of contacts engaging said band and on spaced downstream of the other, and conductors between each of said contacts and a respective side of said source.
 4. The apparatus defined in claim 3 wherein said means includes a third contact engaging said band upstream of said first-mentioned contacts and a conductor connecting said third contact to the same side of the source as the furthest downstream contact.
 5. The apparatus defined in claim 3 wherein at least one of said contacts is a roller.
 6. The apparatus defined in claim 2, further comprising means downstream of said heating station for cooling said band.
 7. The apparatus defined in claim 1 wherein said means coupling said source to said band is an induction coil adjacent said band at said station.
 8. The apparatus defined in claim 7 wherein said source supplies ultrasonic alternating current to said coil.
 9. An apparatus for thermally treating a multiturn continuous synthetic-resin slide-fastener coupling element and having an endless sheet-metal band provided with two transversely spaced mutually parallel upstanding rows of longitudinally spaced tongues bent from said band and forming a series of beds each receiving a respective turn of the element and means for heating the band along a predetermined stretch thereof. 